Chemistry Definition and 993 Threads

  1. Saitama

    Inorganic chemistry, need advice

    I am having a difficult time with this subject. There are so many things to rote memorize here and that's way too difficult for me to rote learn the things. There are loads of reactions, so many reactions for each group, different types of periodic trends, how one can learn or rather, rote...
  2. Q

    Basic thermodynamic chemistry, heat transfer

    Homework Statement How many grams of steam at 100 deg. Celcius would be required to raise the temperature of 35.8 g solid benzene from 5.5 deg Celcius to 45.0 deg Celcius? Assume that heat is only transferred from the steam (not the liquid water) and that the steam/water and benzene are...
  3. E

    Differential Equations in Chemistry

    Hello, I'm a mechanical engineering student working on my senior design project. It involves the automated correction of an electrolyte's chemistry. That being the pH, conductance, and zinc concentration. One of the tasks is to apply a "transient control analysis". This involves creating...
  4. P

    What is the significance of using electron-volts in chemistry?

    Hi all, My instructor in my college chemistry class continually refers to cell potentials (as in battery cell potentials) in units of electron-volts. Is there any case in physics or chemistry where this is correct? My understanding is that an electron-volt is generally a unit of energy, but...
  5. K

    Physical Chemistry: Kinetics and fluorescence

    Homework Statement Consider fluorescence (light emission from an electronically excited state of a molecule) in the presence of a quenching molecule M. Quenching refers to the removal of energy from an excited electronic state by collision, and so without light emission. A mechanism for such...
  6. B

    [Chemistry] Chemical Reaction, limiting reactants and result stoichiometry

    Homework Statement 609.5 grams of vanadium (II) oxide, VO, and 832 grams of iron(III) oxide, Fe2O3, react according to the equation, which substance(s) and how many grams of each would be in the tube after the reaction completes? 3 points Homework Equations Equation: 2 VO + 3 Fe2O3 -> 6 FeO...
  7. A

    What is the process of peptization in chemistry

    I read on a website that by washing a precipitate with too much de-ionised water; the precipitate is Peptized and thus some precipitate is lost. I am having a hard time understanding what peptization is? Can somebody please help me understand in simple terms for an A level student?
  8. Saitama

    Is Inorganic Chemistry by Khadakov a Good Book to Buy?

    Hello all! I have been searching for a good inorganic chemistry book. I came across the book Inorganic Chemistry by Khadakov. This book is by MIR Publishers which is the reason i have made this thread. Unfortunately, since this isn't a popular book, i found no reviews and preview for this book...
  9. Q

    Basic thermodynamic in chemistry, temperature of melting ice

    Homework Statement Consider the heating curve for H2O. a. As heat is added to melt ice, does the the temperature change? Explain what happens to the heat that is added. b. For the same amount of H2O, does it take more to melt ice or vaporize water? Explain why. c. Is the fusion of ice...
  10. H

    Chemistry: Titration of of a base to solve for the mass of an unknown acid.

    A student titrated a .4630g of unknown monoprotic acid with .1060M NaOH. The equivalance point volume is 28.70mL. a) Calculate the number of moles of NaOH used. Im pretty sure I got this one I did .1060 M X .02870L to equal 3.04E-3 mol b)how many equivalents of unknown acid were titrated...
  11. C

    Good software for writing chemistry (chemical equations)

    Hi, what's a good program/software for writing chemical equations, redox reactions etc. I find Office Word to be a bit slow for that (or perhaps it's my who is slow at using it :P ), And I'm having a difficult time compiling oxidation numbers on top of the elements. Any chemistry friendly...
  12. N

    Chemistry Ionic Bonds. Which is the strongest?

    Homework Statement Which has the strongest ionic bond? Cs2Se AlN CaI2 Kbr Homework Equations Look at electronegativities The Attempt at a Solution I looked at electronegativities and found the differences. The largest difference was KBr. But apparently, that was wrong. See EN differences...
  13. A

    Help Me Understand WOW in Chemistry for Panel Discussion

    hi, I have been selected for panel discussion in my university on the event of a Chemistry workshop.i was informed of the subject today and it stated "WOW in chemistry". it has gone over my head and i cannot figure out wat it means . i still wonder if it means the surprising discoveries and...
  14. N

    Physics and Chemistry relationship

    Hi, I'm no expert and I'm still in high school, but I'm curious about the relationship between physics and chemistry. As far as I know Chemistry is based on atomistic theory, right? Well, I'm wondering does physics support atomistic theory entirely or there are some parts of this theory that are...
  15. L

    What Will Poor Performance on the Chemistry GRE Mean for My Application?

    I haven't taken the chemistry GRE exam yet, and I certainty don't plan on doing poorly, but part of me wonders if I did do poorly how if would affect my applications. A majority of the places I am applying to do not require it (but "strongly recommend" it). So if you get in the 50th...
  16. P

    How many grams of Zn reacted in this reaction (very easy chemistry question)

    Homework Statement The reaction between zinc and hydrochloric acid is carried out as a source of hydrogen gas in the laboratory: Zn(s)+2 HCl(aq)\rightarrow ZnCl_2(aq)+H_2(g) If 325 mL of hydrogen gas is collected over water at 25°C at a total pressure of 748 mm Hg, how many grams of Zn...
  17. L

    Help with my unknown in the second organic chemistry

    1. Homework Statement Okay, I just started working on my unknown in Lab and I got stuck with a liquid. First I determined the boiling point, my professor told me to let this step go for 30 minutes and it plateaued at around 147°C. I did this twice the first time I didn't do it as long and got...
  18. Q

    Physical Chemistry water vapor/phases present question?

    23.7 g of water is in a container of 23.7 L at 298.15 . The vapor pressure of water at this temperature is 23.76 Torr. A) What phases are present? B) At what volume would only the gas phase be present? C) At what volume would only the liquid phase be present? A) I know that only the...
  19. Mohamad&Issa

    Chemistry Project Ideas: Exploring Atoms in a Fun and Creative Way

    Hello, We are taking atoms lesson in chemistry and we should have a project for this lesson any ideas for a project?
  20. M

    Physical Chemistry Problem, Evacuated tube - where does reaction take place?

    Homework Statement Two balls, one soaked in concentrated HCl and the other in NH4OH are placed at the left and right ends of a 1m long evacuated glass tube, respectively. HCl and ammonia vaporize and travel down the tube, reacting to form a white ring where they meet. Where does the ring form...
  21. S

    Organic Chemistry - Nomenclature Question

    Homework Statement (see uploaded attachment for picture). I basically have to name this molecule. The Attempt at a Solution I don't know where to start counting for the longest carbon chain and I'm not sure if it's a nonane or octane. If you guys can help it'd be much appreciated
  22. P

    Physical Chemistry- Partial Pressures

    Hello all, This is a homework problem for my CHE345 class. Not sure what to do here, please at least let me know if I'm in the right ballpark. Homework Statement A student decomposes KCLO3 and collects 35.2 cm^3 of O2 over water at 23.0°C. The laboratory barometer reads 751 Torr. The...
  23. F

    Confused by Chemistry? Get Answers Here!

    Is it just so chemistry is extra confusing to students? I don't understand...
  24. N

    Chemistry Acid/base solubility question

    Homework Statement Each of the following salts can be prepared from an acid and a base. Write the balanced molecular equation and the net ionic equation for the preperation of each. indicate states of the reactants and producys . Review solubility rules if neccesary to determine the...
  25. Y

    Physical Chemistry without Previous Chem Experience

    Is it a good idea to take P Chem without taking any chemistry at college level? My high school had a strong chemistry program (we did organic in high school) but I haven't done any Chemistry in college. I am currently taking Quantum Mech 2, and will be taking Thermal Physics and Condensed Matter...
  26. D

    Chemistry's Role in Physics: How Much Knowledge is Required?

    Im taking a 2nd year Chemistry class at my university and I'm struggling. I'm very good a math and physics. How much knowledge of chemistry will you need in physics or a major in physics? I see a lot of sub atomic physics and particles and quantum physics etc.. Will I need to master chemistry?
  27. N

    How Many Ions are Present in 1 Formula Unit of HI, HBr, and N2S5?

    Homework Statement How many ions are present in 1 formula unit of HI(aq)? HBr(g)? N2S5? Homework Equations These two questions have the same concept, I believe. I went the simple way and thought the answer was 2 for both of them, but apparently that was wrong. Can someone show me how to...
  28. N

    Quantum Mechanics and Electron Configuration in a Modified Universe

    Homework Statement In a universe different from ours, the laws of quantum mechanics are the same as ours with one small change. In this different universe the m ℓ quantum number obeys this rule. mℓ = (-ℓ-1), (-ℓ),..,0,...(ℓ), (ℓ+1) In this different universe, what is the maximum number...
  29. N

    Courses Uni course- Biophysical Chemistry, or Physical chemistry

    Uh, my program is Biotechnology/biochem (might change it). I can take a "Biophysical chemistry"or a "physical chemistry" mind you, I am strugging to even pas year one physics i hate it and it sucks. So I really want something with not as much math. Does anyone know if biophysicalchem has less...
  30. M

    General Chemistry - Heat, Work, Enthelpy, Entropy Question

    1. Assume that one mole of H2O(g) condenses to H2O(l) at 1.00atm and 95 Celcius. Calculate q, w, ΔH, ΔS of the system, ΔS of surroundings. BUT I AM NOT ASKING HOW TO CALCULATE THESE VALUES, SEE LAST SENTENCE OF POST. Homework Equations q = nCΔT ΔH = n(Cp)ΔT W = -PΔV ΔS = [q_reversible] / T Cp...
  31. A

    Analytical Chemistry - Systematic Treatment of Equilibrum

    Homework Statement Calculate the molar solubility of Ag2C2O4 (silver oxalate) in a solution that has a fixed H3O+ concentration of 1.0 x 10^-6 M. Homework Equations The Attempt at a Solution I found the pertinent reactions, the charge balance and the mass balance so far, but I...
  32. H

    Analytical Chemistry- Ksp problem help

    Homework Statement Find the concentration of Pb2+ in 0.0010 M KI with PbI2. Include activity coefficients in your solubility-product expression. The Ksp of PbI2 is 9.8*10^-9 Homework Equations Ksp= [Pb2+]\gammaPb2+[I-]2\gamma2I- Assume that [I-]=0.0010 M. The ionic strength of 0.0010 M Ki...
  33. P

    Chemistry- Electronic Transitions Urgent help

    the energies of light quanta increase gradually as the color of light changes. Of the following metals, which has the largest energy change: sodium, barium, calcium, strontium, lithium, potassium, and copper (ll) I need this within half an hour :cry: I'm guessing it has something...
  34. M

    Why Is Organic Chemistry So Challenging for Some Students?

    I am having difficulties studying for organic chemistry. The concepts don't seem especially difficult, but I am not performing where I want to be at in this class (1st semester organic chemistry). I do fine in math and physics, and even did well in general chemistry, but it seems the skills...
  35. C

    Good 101 chemistry books? and databooks?

    Hi. I'm looking for a good 101 chemistry book (still big in size) for university. The kind of all around book with all the useful formulas, and explanation for how they are used. Another type of book I'm looking for is a good datebook for chemistry, with all the table values such as ΔH ΔS...
  36. A

    How long does it take you to write a prelab or lab report for chemistry lab?

    How long does it take you to write a prelab or lab report for chemistry lab? And what grades do you usually get for these assignments? I spend like at least 2 hours writing a lab report because I want to get a perfect grade. Also, I spend quite a lot of time on a prelab too, because I'm scared...
  37. L

    How to properly prepare for org. Chemistry exam?

    Hi, First of all, I don't have much difficulties learning stuff for exams in general. Though, organic chemistry seems to be the hardest subject I ever had. Not because I find it too difficult to understand, it's because of the quantity. I don't really know how to properly prepare for my exam...
  38. T

    Physical Chemistry- Using the integrated Vant Hoff Equation with K values.

    Homework Statement The equilibrium concentration of oxygen in fresh water exposed to the atmosphere is given for two temperatures. At 15 degrees celcius equilib [O2]= 630μmol/L at 25 degrees celcius equiln [O2]= 517μmol/L The expression for the equilibrium constant, K, between the oxygen...
  39. mishima

    What Makes Things Work? A Chemistry Exploration for High School Students

    I was looking for something like Bloomfield's "How things work" but for chemistry rather than physics. Audience is high school kids in a first chemistry course.
  40. 9

    Chemistry Minor in Math or Chemistry for ChemE?

    Hi everyone, My major is Chemical Engineering and I'm very indecisive about choosing a minor. My options are math and chemistry. Should I minor in both or just one? I don't know which minor would help me the most when I go out looking for a job in the future? I'm planning to attend Grad...
  41. S

    How Do You Calculate the Heat Capacity of a Liquid?

    Can anyone help me with a chemistry ? When 47.5 J of heat are added to 13.2 g of a liquid, its temperature raises by 1.72 degree Celsius. What is the heat capacity of the liquid?
  42. Saitama

    How do you study Organic Chemistry?

    I suppose this is the right place to post this. I have been studying organic chemistry from more than three-four months and i can't even remember the basic reactions. There seems to be so many reactions which i need to memorize. Whenever i sit to do questions on the reactions, i always need to...
  43. A

    Calculating Air Volume and Composition with Physical Chemistry Principles

    A mole of air (80% Nitrogen, and 20% Oxygen by volume) at 298.15K is brought into contact with liquid water which has a vapor pressure of 3168 Pa at this temperature. a) what is the volume of the dry air if the pressure is 1 bar? b) what is the final volume of the air saturated with...
  44. R

    Partial Derivatives Applied to Chemistry

    Homework Statement Please look at the attached pic. I don't know how to type all these symbols in. Homework Equations Im not sure how to start The Attempt at a Solution I tried using the cyclic rule but the problem just started getting messier.
  45. X

    What Are the True and False Statements About Hydrogen Electron Transitions?

    Homework Statement The hydrogen electron de-excites from its 3rd excited state, which are the true and false statements for it. 1. It emits radiation giving lines in Lymann, Balmer, Paschen series 2. It emits radiation of only UV and Visible region and not Infrared region 3. It emits radiation...
  46. K

    Statistics Problems from Physical Chemistry

    Homework Statement The following data were obtained for trace elemental zinc in a particular sample of high purity (%Au> 99.99%). The results are given in mg Zn/ kg Au. 15.38, 15.17, 15.33, 14.88, 14.71, 15.42, 15.60, 15.22 Find the zinc content and the uncertainty at 95% confidence...
  47. B

    Anyone want to critique a lab report (chemistry)?

    Homework Statement I've not written a lab report since prep school and I need some critiques (thorough). see attached Homework Equations The Attempt at a Solution
  48. N

    Chemistry Sig Digs Problem: Finding Thickness of Metal Sheet - Homework Solution

    Homework Statement A sheeet of metal is 19.3mm wide and 48.2.mm long. if it weighs 8.171g and the density of the metal is 6.69g/cm63, what is the thickness in mm? Homework Equations V= L*W*H H=V/L*W D=M/V V=M/D The Attempt at a Solution 8.161g(4sig)/6.69g/cm^3(density, so sig...
  49. I

    Calculus for Chemistry Majors: Overcome Struggles & Prepare for Grad School

    I was wondering as to just how deeply chemistry relies on calculus. I'm great at all my chemistry homework and studies, but calculus is a real struggle for me. Not that it's impossible, just with the resources I have it's incredibly difficult. I worry that in the future, as in when I get to grad...
  50. Z

    Organic Chemistry - 1H and 13C NMR Problem. HELP

    Homework Statement Determine the structure of the compound given the information belowHomework Equations Molecular Formula: C8H6O4 1H NMR: 1.57 (d, J=8.66 Hz, 1 H) 1.77 (d, J=8.66 Hz, 1 H) 3.51 (d, J=3.00 Hz, 1 H) 3.51 (d, J=3.00 Hz, 1 H) 3.60 (sc,J=7.56, 3.00 Hz, 1 H) 3.60 (sc, J=7.56, 3.00...
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